A conventional door locking device shown in FIG. 24 is configured to rotate a lock switch member 2 to a lock position and to an unlock position by means of a power of a motor, and lock and unlock a door. According to this door locking device, a key operation transmission member 3, which is formed in a fan shape and rotates in response to a key operation of a key cylinder (not shown in the drawing) provided at the door, is provided at a lateral side relative to the lock switch member 2. Then, a key operating force is transmitted from the key operation transmission member 3 to the lock switch member 2 so that the lock switch member 2 is switched to the lock position and to the unlock position also by means of the key operation of the key cylinder. In addition, in order that the key cylinder does not move from a neutral position without the key operation, it is configured that a force is not transmitted from the lock switch member 2 to the key operation transmission member 3. Specifically, a distal end portion of an engagement arm 5, which extends from the lock switch member 2, is received dated between a pair of contact portion protruding portions 4, 4 which are included in the key operation transmission member 3. Then, in a case where the key operation transmission member 3 is rotated to a key lock position and to a key unlock position by the key operation operated relative to the key cylinder, the engagement arm 5 is pushed by either of the contact portion protruding portions 4, and the lock switch member 2 rotates to the lock position and to the unlock position. On the other hand, even when the lock switch member 2 rotates to the lock position and to the unlock position in a state where the key operation transmission member 3 is positioned at the neutral position, the engagement arm 5 does not push the contact portion protruding portions 4, 4 but rotates between the contact portion protruding portions 4, 4, and the key operation transmission member 3 is configured to be kept at the neutral position (for example, see Patent Document 1).